Independent and integrated skin sensory contributions to postural control

为了保持平衡，人类必须利用视觉、前庭和体感信息。我的研究项目的长期目标是了解生理机制，使来自皮肤、肌肉和前庭系统的信息能够调节正在进行的任务，并在站立和行走时产生适当的姿势反应。我的直接目标是研究皮肤对踝关节周围本体感觉的作用机制，并确定个体受体类型的作用。脚底皮肤输入的减少导致平衡不足，证明了脚底皮肤在平衡调节中的作用。最近的研究也表明，手指、肘关节和膝关节周围的皮肤与关节位置感和本体感觉有关。这一点尤其重要，因为我们知道人类走路时脚的间隙很小，这使我们容易绊倒，因此依赖于准确的脚踝位置。我们的工作旨在进一步了解来自下肢的皮肤输入，重点关注脚踝皮肤和脚尖，因为该区域的皮肤可以很好地提供有关脚踝角度的信息。这项工作的第一个目标是确定皮肤与纺锤体输入相互作用的机制，以帮助监测脚踝角度。通过使用微神经摄影技术，记录人类的单个传入神经纤维，我们可以分离个体类型的皮肤和肌肉传入神经。这将使我们能够评估这些感觉源是如何相互作用的。我们也知道有四种不同类型的皮肤受体（快速和缓慢适应，I型和II型），每种受体都提供独特的输入，导致猜测每种受体在平衡和运动中可能有独特而重要的作用。因此，第二个目标是分离不同类型的受体如何参与关节位置感、速度感和感觉输入（纺锤体和其他皮肤受体）的调节。最终提出的工作将研究皮肤如何独立作用，并作为其他感觉源的促进者。这项工作将使我们更接近了解皮肤对静态和动态姿势控制的影响和程度。

To maintain balance, humans must utilize vision, vestibular and somatosensory information. The long term objective of my research program is to understand the physiological mechanisms which enable information from the skin, muscles and vestibular system to modulate ongoing tasks and generate appropriate postural responses during standing and walking. My immediate goal is to investigate the mechanisms by which skin contributes to proprioception around the ankle, and identify contributions from the individual receptor types. Decrements in skin input on the foot sole result in deficiencies in balance, demonstrating a role for foot sole skin in balance regulation. Recent work has also shown that skin around the finger, elbow and knee joints contributes to joint position sense and proprioception. This is particularly relevant as we know that humans walk with minimal foot clearance, leaving us susceptible to tripping and therefore dependent on accurate ankle position. Our work aims to further what we know about skin input from the lower limb, with a focus on ankle skin and the top of the foot, since skin in this area is well placed to provide information regarding ankle angle. The first objective of this work is to identify the mechanism by which skin interacts with spindle input to help monitor ankle angle. By using the technique of microneurography, where recordings are made from single afferent nerve fibres in the human, we can isolate individual types of skin and muscle afferents. This will enable us to assess how these sensory sources interact. We also know there are four different types of skin receptor (Fast and slowly adapting, Type I and II) each providing unique input, leading to speculation that each type of receptor may have a unique and important role in balance and locomotion. The second objective is therefore to isolate how the different types of receptor contribute to joint position sense, velocity sense and modulation of sensory input (spindle and other skin receptors). Ultimately the proposed work will study how skin acts both independently and as a facilitator for other sensory sources. This work will bring us one step closer to understanding the impact and extent of skin's influence on static and dynamic postural control.